Heat transfer device



March 21, 1944. w, L LT 2,344,588

HEAT TRANSFER DEVICE Filed Jan. 6, 1941 2 @Sheeis-Sheet 1 InventorWarren 5. Blauvelc,

His Attorney.

March 21, 1944. s, BLAUVELT 2,344,588

HEAT TRANSFER DEVICE Filed Jan. 6, 1941 2 Sheefs-Sheet 2 Inventor y K/,His Attorney Warren 5. Blauvelt, I

Patented Mar. 21, 1944 HEAT TRANSFER DEVICE Warren S. Blauvelt, AnnArbor, Mich, assignor to Blauvelt Associates, Inc., Troy, N. Y., acorporation of New York Application January 6, 1941, Serial No. 373,211

1 Claim.

One of the objects of my invention is the provision of a relativelyinexpensive, compact and thermally efficient device for the transfer ofheat from one gas, vapor or mixture thereof to another gas, vapor ormixture thereof in their passage therethrough. Throughout thespecification and claims I shall, for convenience, refer to the gases,vapors or a mixture thereof simply as gases, intending thereby to covergases, vapors or mixtures thereof.

The device embodying my invention may be used for various purposesnecessitating a variety of designs. For example, it may be used topreheat air for combustion by abstracting heat from ,the combustiongases leaving a furnace in which case the total weight of air passingthrough the heat transfer device may be of the order of 90% of theweight of the combustion gases passing through said device during anygiven period. Likewise, it may be used to transmit heat from combustiongases from a warm air heating furnace to the circulated air in whichcase there may be twenty-five times as many pounds of air heated in agiven period as there are pounds of combustion gases cooled.

One of the objects of my invention is the provision of a novelcombination of ducts for the passage of heated gases, usually combustiongases, and of gases to be heated, so associated as to facilitate thetransfer of heat from the one gas to the other, with corrugated bafflesso disposed in both the ducts that carry the hot gases and in those thatcarry the gases to be heated as to create turbulence in the gases andreduce the thickness of the viscous film which adheres to the walls ofthe ducts and retards the transfer of heat therethrough.

Other objects of my invention will appear in the specification and thenovel features thereof will be pointed out in the claim.

My invention will best be understood by refer ence to the accompanyingdrawings in which I have illustrated preferred forms thereof and inwhich Fig. 1 is a plan view of one form of the heat transfer deviceembodying my invention;

Fig. 2 is a sectionai elevation taken along the line 2-2 of Fig. 1looking in the direction of the arrows;

Fig. 3 is a sectional view taken along the line 33 of Fig. 1, looking inthe direction of the arrows;

Fig. 4 is an end elevation of one of the baiiies over which heated gasflows and the support therefor;

Fig. 5 is an end elevation of one of the baflles which is disposed in aduct and the supportstherefor;

Figs. 6, 7, 8 and 9 are sectional views taken through the baiiies whichare disposed in the air ducts and the supports therefor, the fourfigures showing the battle in different positions with respect to thewalls of the ducts within which they are located; and

Fig. 10 is a perspective view, partially broken away, of a heat transferdevice in which the heated gases flow through respective ducts in adirection at substantially right angles to the direction of flow of thegases to be heated.

Like reference characters indicate like parts throughout the drawings.

The heat transfer device proper embodying my invention comprises endplates l0 and II which are lower and upper plates in Fig. 2 and whichare provided with spaced slots in which are inserted spaced ducts [2 ofrectangular cross section the ends of which are welded or otherwisesealed to said plates I 0 and H and which ducts l2 serve to carry theheated gases which flow upwardly from a common inlet l3 (Fig. 3) throughthe ducts l2 to a common outlet M as best indicated in Figs. 2 and 3.Each of the long side walls ii of each of the said heated gas ducts l2serves also as a side wall of a duct ll through which the air to beheated flows. In the embodiment of my invention here illustrated, outerwalls 45 are side walls for the air ducts I? through which the gas to beheated flows. The heated gas in the embodiment of the invention hereillustrated flows upwardly through the ducts i2 and the gas to be heatedflows in a substantially horizontal direction through the air ducts ii.A common inlet 18 for the air leads to one side of the heat transferdevice through which it is distributed to the air ducts it through whichit flows transversely of the heat transfer device to a common air outletit as best indicated in Figs. 1 and 3 from which the air flows to theplaces where it is to be used. The heat of the heated gases is thustransferred through a common wall it between the gas duct i2 and the airduct ill to the air to which heat is to be transferred.

When heat is thus to be transferred through a plate or wall, there ispresent a viscous film of gas that clings or adheres closely to the walland which serves as a heat insulating material which retards the flow ofheat to and from the wall.

In accordance with my invention means are provided for causingturbulence of flow of gas through the ducts carrying both gases orvapors from which heat is to be transferred and those carrying the gasesor vapors which are to be heated, thereby reducing the thickness of theviscous films from the wall or walls of the ducts and thus facilitatingthe transfer of heat. In accordance with my invention corrugated bafiieplates are disposed in both the ducts which carry the heated gases andalso in the ducts which carry the gases to be heated, the bafile platesbeing provided with alternating crests and valleys preferably angular inform at their edges arranged substantially at right angles to thegeneral direction of flow of gas thereover and which cause turbulence inthe flow of gases thereby reducing the thickness of the viscous filmadhering to the common wall through which heat is to be transmitted fromone gas or vapor to another.

Referring particularly to Figs. 4 and 10, I have indicated a bafileplate 20 disposed in a heated gas flue i2, the bafile plate having itsends in common planes and received in an opening 2| in one side of asupport 22 as best indicated in Figs. 4, 5 and 10. The heated gases,therefore, flow upwardly across the crests and valleys of the baffleplate 20 on either side thereof.

The flow areas between the crests of the baiile plates and the walls ofthe duct, progressively decrease from the lower and hotter end of thebaffle plate to the upper and cooler end thereof thereby decreasing theflow areas of the gases as their volume decreases.

In the embodiment of my invention illustrated in Figs. 1 to 10, thereare thus formed a plurality of ducts I2 (Fig. in which the heated gasesflow upwardly.

The air or other gases or vapors to be heated flow through the ducts ina direction, in the embodiment illustrated, substantially at rightangles to the upward flow of the heated gases. In

Fig. 2 each of these air ducts i1 is divided into a plurality of ductsby the supports 22 of the baffie plates 20.

When the flow areas between the bafiie and the adjacent wall areprogressively decreased in the direction of the flow of gases, the slot2! in which the bafile plate is received is tapered outwardly asindicated in Fig. 4 in the direction of the flow of gases.

Referring to Figs. 6, '7, 8 and 9 it will be noted that the bafile plateis differently placed relatively to its distance from the side walls ofthe ducts in which the bafile plate is placed. In Fig. 6 and in Fig. 7the bafile plates are placed centrally between the side walls so that ineach case the distance from the crest of the baffle to the side wall issubstantially the sameon each side of the baiile plate. Figs. 8 and 9illustrate positions of the baffle plates in the outside duct ll whereonly one of the side walls of said duct is also a side wall of a gasduct. The distance of the battles from the side wall which is also theside wall of the adjacent hot gas duct is greater than the distance ofthe baiiies on the other side of the baille plate from the outside wallof duct ii, the relative distances of the bafile edges from the two sidewalls of the duct being determined by the desired temperature at whichthe gases to which heat is to be transmitted leave the heat transferdevice.

It will be understood that the device embodying my invention not onlycreates turbulence in both the heated gases and the gases to be heated,thereby partially removing the viscous film from the walls of thedevice, but heat is also transmitted by radiation from the hot gasbaffles which absorb heat from the heated air and transmit it to thecommon wall between the hot air duct and the duct carrying gases to beheated.

The device embodying my invention has been found to be highly eificientin operation and is of comparatively inexpensive construction.

Under some conditions instead of having baffie plates of the characterdescribed installed in the ducts carrying the gas to be heated, othermeans for facilitating the transfer of heat may be used. For example,when the gases are to be cooled from 2700" F. to 200 F. by transfer ofheat to air which may be heated from F. to F., the ducts carryingtheheated gases could be the same as those already described, while theair ducts would have no separate baffie plates of the characterdescribed but the common wall between adjacent ducts might be providedwith fins projecting at substantially right angles therefrom into theair duct.

While I have described my invention in its preferred embodiment, it isto be nderstood that the words which I have used are words ofdescription rather than of limitation. Hence, changes Within the purviewof the appended claim may be made without departing from the true scopeand spirit of my invention in its broader aspects.

What I claim is:

In a heat transfer device, a first duct and a second duct, eachsubstantially rectangular in cross section andhaving a common fiat walltherebetween, means for causing gases to be cooled to flow through saidfirst duct, means for causing gases to be heated to flow through saidsecond duct in a general direction substantially at right angles to thegeneral direction of flow of gases through said first duct, a baffleplate means for supporting said plate within said first duct, saidbaflle plate being provided with alternating crests and valleysextending substantially at right angles to the general direction of flowof gases through said first duct, the distanc of the crests of saidbaille plate from the walls of its duct progressively decreasing in thedirection of flow of gases through said first duct.

WARREN S. BLAUVELT.

